This invention relates to plastic reinforced fiber products and more particularly, to plastic reinforced glass fiber fishing-rods.
Glass fiber fishing-rods have been generally referred to as glass fishing rods and are well known in the art.
There have been proposed and practically employed a number of methods for producing plastic reinforced glass fiber fishing-rods. In one of the conventional methods as shown in FIGS. 1 and 2, a piece of trapezoidal glass fiber fabric 2 which has been preliminarily impregnated with liquid thermosetting plastic is wound about a tapered mandrel 1 in an annular form with the narrower width end of the fabric directing to the reduced diameter end of the mandrel, and then a cellophane tape 3 is wound about the glass fiber fabric 2 in a spiral form. The thermosetting plastic in the thus-formed assembly is set by heating the assembly at a temperature within the temperature range of 140.degree.-180.degree. C. for about 0.5-2 hours and thereafter, the mandrel 1 and cellophane tape 3 are removed from the stiffened glass fiber fabric 2 to thereby obtain a desired plastic reinforced glass fiber fishing-rod. Although the thus-obtained glass fiber fishing rod is tough, since the specific gravity of the glass fibers of the glass fiber fabric is 2.7, the fishing-rod has the disadvantages that the fishing-rod is relatively heavy and that the fishing-rod is too flexible for its intended use.
Carbon fiber generally has a strength greater than glass fiber and the coefficient of elasticity of the former is quite a bit smaller than that of the latter and therefore, when a fishing-rod is formed of carbon fibers, such a fishing-rod has a stiffness suitable for its intended use. Furthermore, since carbon fiber has the specific gravity of 1.8 which is substantially lighter than that of glass fiber, the fishing rod formed of carbon fibers is quite light in weight. However, since carbon fiber is a very expensive material, if a fishing-rod is produced from a carbon fabric which comprises 100% carbon fibers, such a fishing-rod is economically impractical. Furthermore, since carbon fiber is low in elasticity and rather stiff, the tip end of a fishing-rod formed of a carbon fabric comprising 100% carbon fibers has to have imparted thereto an additional elasticity by a specific means depending upon the purposes for use. Therefore, it has been conventionally considered that plastic reinforced fishing-rods are required to be produced by the use of glass and carbon fibers in combination.
As one of the conventional methods of producing a fishing-rod by the combined use of glass and carbon fibers, as shown in FIG. 3, for example, a piece of trapezoidal glass fiber fabric 2 similar to the glass fiber fabric 2 shown in FIGS. 1 and 2 is wound about a tapered mandrel 1 similar to the mandrel 1 shown in FIGS. 1 and 2 in the same manner as described in connection with FIGS. 1 and 2. However, in the example of FIG. 3, a bundle of carbon fibers 4 having substantially the same length as the glass fiber fabric 2 and impregnated with the same thermosetting plastic as that employed in the glass fiber fabric 2 is interposed between adjacent turns of the glass fiber fabric 2 covering a distance in the transverse direction of the glass fiber with carbon fibers extending in the longitudinal direction of the mandrel 1 while the glass fiber fabric is being wound about the mandrel to provide an alternate spiral cross-section or alternatively, each bundle of such carbon fibers 4 is interposed between each adjacent turn of the glass fiber fabric covering a shorter distance in the transverse direction of the glass fiber fabric 2 in a similar manner in an offset relation to other bundles of long carbon fibers interposed between other successive turns of the glass fiber fabric. In such a case, the long carbon fibers are not woven, but merely orientated flat in the same longitudinal direction as they are. Although the fishing-rod produced by the method shown in FIG. 3 has great strength in the longitudinal direction because the long carbon fibers are present in that direction, since no carbon fibers are preseent in the direction at right angles to the longitudinal direction, the strength of the fishing rod in the direction at right angles to the longitudinal direction is not sufficient. Thus, in the production of a fishing-rod by the combined use of glass and carbon fibers as shown in FIG. 3, it is necessary that some of the long carbon fibers be orientated at an angle with respect to the other long carbon fibers or that another fiber fabric or fabrics be employed in combination with the long carbon fibers.
FIG. 4 shows another conventional method for producing a fishing-rod by the combined use of glass and carbon fiber fabrics. In the method of FIG. 4, a piece of glass fiber fabric 2 and a piece of carbon fiber fabric 4a having the same trapezoidal shape are connected together with the adjacent longitudinal edges thereof over lapping one another. As mentioned hereinabove, the glass and carbon fiber fabrics 2 and 4a are preliminarily impregnated with the same liquid thermosetting plastic as employed in the glass fiber fabric 2 and carbon fibers 4 of FIG. 3. Referring back to FIG. 4 again, the connected glass and carbon fiber fabrics 2 and 4a are wound about a tapered mandrel 1 similar to that described hereinabove in connection with the methods of FIGS. 1 through 3 with the narrower width end portions of the two fabrics directing to the reduced diameter end portion of the mandrel 1. In the method of FIG. 4, if the glass and carbon fiber fabrics 2 and 4a are connected together with the adjacent longitudinal edges thereof lapping one upon another by great lapping depth or width, a laminated spiral structure in which the glass and carbon fiber fabrics form alternate layers is obtained or alternatively, if the glass and carbon fiber fabrics 2 and 4a are lapped along their longitudinal edges in a small lapping depth or width, the obtained structure will have a substantially circular cross-section. The method of FIG. 4, is designed so that the glass fiber fabric 2 is surrounded by the carbon fiber fabric 4a in the laminated structure, but it is also possible that the carbon fiber fabric 4a to be surrounded by the glass fiber fabric 2 in the laminated structure.
The methods shown in FIGS. 3 and 4 have a common in that a fishing-rod is produced by combining glass and carbon fibers together in the same percentage or selected different percentages and in order to impart a high strength in the longitudinal direction of the fishing-rod especially, the warp yarns of both the glass fiber fabric and the long carbon fibers or the warp yarns of the carbon fibers extend parallel to each other in the longitudinal direction of the fishing-rod. In other words, the methods of FIGS. 3 and 4 are mere modifications of the method shown in FIGS. 1 and 2 because a portion of the glass fibers employed in the method of FIGS. 1 and 2 is replaced by the carbon fibers.
The method shown in FIG. 5 is somewhat different from the methods referred to hereinabove. According to the method of FIG. 5, long carbon fibers 4b are placed along the length of a tapered mandrel 1 similar to the mandrel described in connection with the preceding methods and then a single continuous length of glass fiber yarn 6 is wound about the long carbon fibers 4b in a spiral form. It should be understood that both the carbon fibers 4b and glass fiber yarn 6 are preliminarily impregnated with the same liquid thermosetting plastic. In this method, the fibers which impart a desired strength to the fishing-rod in the longitudinal direction thereof comprise only the carbon fibers 4b and only the fibers of the glass fiber yarn 6 are positioned to maintain the circular cross-section configuration of the complete fishing-rod. Although this method uses the carbon and glass fibers in combination, the two types of fibers are employed for different purposes, respectively and thus, the fishing-rod produced by the method of FIG. 5 may be referred to as a 100% carbon fishing rod. However, the fishing-rod produced by this method has insufficient strength in the longitudinal direction for its intended purpose because the shape maintaining capability of the single glass fiber yarn 6 is not sufficient.
In the method shown in FIG. 6, a bundle of long carbon fibers 4c is placed surrounding and extending the length of a tapered mandrel 1 similar to that described in connection with the preceding methods. Then, a piece of glass fiber fabric 7 in the form of a tape is wound in a spiral form about the carbon fibers 4c in one direction at a suitable angle to the axis of the mandrel 1 with no clearance left between the side edges of the adjacent turns of the tape and finally, a piece of similar glass fiber fabric 8 in the form of a tape is wound in a spiral form about the previously wound glass fiber fabric tape 7 in the opposite direction at a suitable angle to the longitudinal axis of the mandrel intersecting the tape 7 with no clearance left between the adjacent turns of the tape 8. In this method, since the carbon fibers 4c and the fibers of the tapes 7, 8 are merely applied in discrete layers and are not interwoven, the strength of the produced fishing-rod in the longitudinal direction is insufficient for its intended purpose. And the method of FIG. 6 requires a rather complicate forming procedure. Also in the method of FIG. 6, it should be understood that the carbon fibers 4c and the glass fiber fabric tapes 7, 8 are preliminarily impregnated with the same liquid thermosetting plastic as employed in the methods of FIGS. 1 through 5.
The thermosetting plastic employed in the methods referred to hereinabove may be one member selected from the group comprising phenol, epoxy, polyester and the like which are especially useful in the production of small diameter hollow elongated products such as fishing-rods which require substantial strength. These plastics are heat-set at a high temperature within the range of 140.degree.-180.degree. C. at which the thermosetting plastic is set. While the carbon fibers have a very small coefficient of thermal expansion, the glass fibers have a very great coefficient of thermal expansion. Therefore, when the glass and carbon fiber layers are placed one upon another and heated at a high temperature within the range of about 140.degree.-180.degree. C. for about 0.5-2 hours, the two layers are prefectly secured together by means of the set thermosetting plastic and thereafter they are allowed to cool in open air. Since the glass fibers have a great coefficient of thermal expansion, when cooled, the glass fibers shrink by a substantial amount. As the result, a substantial internal distortion occurs within the produced fishing-rod resulting in a substantial warp of the fishing-rod. Even when the fishing-rod is bent by a small degree with an external force, the so-called layer separation phenomenon occurs. The above-mentioned conventional methods have the disadvantage they are not applicable to fishing-rods of high quality.